Comparing two different controller designs for evolving robots Ferenc Havasi Vincenzo Giordano Michael Schwarz Gregory Valigiani Stefan Wiegand Thanks to Marc Schoenauer and Nicolas Godzik

Evolutionary robotics The control system of the robot evolves through ES The fitness function is set according to the task to be performed Explorative evolution, minimal human intervention

Advantages 1.self-organization, no explicit design 2.Exploitation of the interactions between the robot and the environment 3.No decomposition in and integration of (hopefully) simpler tasks 4.No need of many assumptions (not knowledge-rich representation)

Disadvantages The automatic process of adaptation on real-robots is time-consuming Need for heuristic and rules of thumb (trial and error procedures) Lack of formal principles: It’s difficult to compare slightly different experiments

Main point What happens if we add more knowledge in the evolution process? Are we reducing capability of evolution of exploring? Are we reducing capability of evolution of generalizing?

Two different architectures

Experimental set-up Tasks Structure of the neural network (try simple ones before) Structure of the evolutionary strategy: (20,140)-ES with weak elitism Fitness function (as simple as possible)

Experiments Obstacle avoidance fitness= high speed*straight motion*low sensor activation Following a moving object same fitness but if the camera is on then slow down and go straight

Obstacle avoidance

Following the object

Generalization We want to measure the ability to generalize the acquired knowledge to novel circumstances We evaluate the last generation of individual for each run in a different environment

Generalization (obstacle avoidance)

Generalization (following object)

Conclusions 1.The ‘following object experiment’ was successfull with both controllers 2.The second controller seems to perform better and to evolve faster than the first one 3.More specific design doesn’t necessarily lead to better results 4.It’s necessary to test generalization capabilities performing different tasks